Part No. 4011
Part No. 4012
Weight (oz)
10 x 6


PLEASE READ ALL SAFETY INSTRUCTIONS! Failure to read, understand and follow these instructions could result in personal injury and/or property damage to yourself or others.

Take a few moments to familiarize yourself with the various parts of the engine. DO NOT DISASSEMBLE YOUR ENGINE! Doing so will void your warranty. No exceptions!


It is unnecessary to give the engine a prolonged break-in. However, we suggest that you mount your engine to a break-in stand to familiarize yourself with it and with the carburetor operation. It is strongly recommended that fuels containing more than 15% nitromethane be avoided until after the engine has been in operation for about an hour on a mild fuel, and under mixture-rich conditions. Mixture-rich operation is when the engine has a slight “burbling” sound and probably a very smoky exhaust. This helps lubrication and cooling when the engine is new.

Typically, an engine will be ready for full-throttle and mixture-lean operation after less than an hour of running. When the engine holds R.P.M. after the mixture has been leaned out ... when R.P.M.’s don’t sag after a moment or so ... the engine can be considered to be broken in.


The engine may be installed upright, on either side, or inverted (upside down). The 1/4 inch diameter output shaft mounts standard hole-size propellers.

Mount the engine firmly to hardwood rails, or to the firewall, if you use a radial mount. For maximum security, use carbon steel, self-locking hex nuts and hardened alloy steel machine screws to mount the engine. The fuel tank size, location, and height have a great influence on engine operation. For carburetor engines, locate the tank so that its horizontal centerline is from 1/4” to 3/8” below the fuel connection to the carburetor.


With a full tank of fuel, the recommended propeller installed, and a fully-charged booster battery of no more than 1.5 volts ready for connection to glow plug, proceed as follows to manually start an engine installed in a plane.

NOTE: To avoid burning out the glow plug, never use a booster battery of more than 1.5 volts. The battery is used to heat the glow plug coil only during engine starting. After the engine has started and is running smoothly, the booster battery is disconnected. Heat from the burning mixture in the cylinder keeps the coil hot.

1.  With the booster battery disconnected, turn the needle valve counter-clockwise 2-1/2 turns from the fully closed position.

2.  With the booster battery still disconnected and with the throttle wide open, place finger tip over the carburetor inlet and flip the propeller quickly 2 or 3 times, to prime the engine.

3.  Remove finger tip from the carburetor inlet then close the throttle to a fast idle setting and again flip the propeller quickly 2 or 3 times.

4.  Connect the booster battery clip to the glow plug.

NOTE: Make sure you are holding your airplane firmly to prevent it from lurching forward when the engine starts. After it starts, maintain your hold until you have reduced the throttle to a low idle speed.

5.    Slowly turn the propeller (counter-clockwise) and “feel” for a momentary resistance, which indicates ignition of the mixture in the cylinder.

6. Quickly flip the propeller to start the engine and then disconnect the booster battery.

7. Except for the first hour or so, as noted under “Engine Break-in”, adjust the needle valve by turning clockwise to lean the mixture for full power operation. If the R.P.M. starts to sag (back-off) you have leaned the mixture too much and you should then turn the needle valve counter-clockwise until the R.P.M. picks up and holds steady.


The carburetor enables easy adjustment of both the idle speed and idle mixture. Install needle valve by screwing it in all the way to its seat, then unscrew 2-1/2 turns. This will be a rich setting after engine starts. Screw in to desired setting (not too lean) Low Speed Disk is preset at factory.

NOTE: Always adjust idle speed first and idle mixture last. Typically, it will be necessary to go back and forth several times to get both the engine idle speed and idle mixture adjusted properly.

Turn the idle speed screw clockwise to increase speed; counter-clockwise to decrease speed. Turn the idle-mixture screw counter-clockwise to enrich the mixture; clockwise to lean the mixture. Typically, an idle speed of 2300 R.P.M. is a dependable idle setting.



Locate an area to install the remote needle valve assembly. This assembly must be in the fuel line between the tank and the carburetor. The line should not exceed five (5) inches in total length.


A 10x6p propeller is recommended as a starting size. However, experimenting with one pitch or diameter larger or smaller can improve results for your particular airplane.


This engine comes equipped with a standard Long Reach Glow Plug (K&B No. 7311). Performance will vary, depending on the glow plug and fuel used.

Idlebar Long Reach, K&B No. 4520
Max R.P.M.
Idle R.P.M.

Above comparisons are with a 10”x6p wood propeller and K&B 500 fuel.

Dust and dirt are the worst enemies of your engine. At all times, keep the engine and the fuel clean. Wipe engine surfaces clean with a rag dipped in a solvent such as methanol or paint thinner, or use a soft-bristle, metal brush to clean engine surfaces.

Long-life engine operation where dusty conditions prevail requires the use of an air filter at the carburetor. The filter must be able to clean the air of dust particles without creating an unnecessary restriction to air flow into the engine. An air filter must be cleaned or replaced frequently, depending on its design.


Improper fuel/air mixtures, bad ignition, worn-out carburetors, or weak cylinder compression are the main causes of hard starting, poor power, slow throttle response, or unreliable engine idle.

Fuel/air mixtures cause trouble if there is too much or not enough fuel admitted to the cylinder which can result from improper fuel tank height, design or needle valve adjustment; leaking, kinked or plugged fuel lines; leaking connections, or a bad fuel tank vent.

Ignition can be the cause of starting trouble if (a) the booster battery is weak or dead, (b) there are bad connections to the battery or the plug, or, (c) the glow plug coil is burned out. Ignition can be the cause of trouble after the booster battery is disconnected if (a) the glow plug has an air leak at the center post or around the gasket, (b) if the glow plug coil is burned out.

Compression is evident if the engine has good resistance when it is cold and being turned through by hand. Little or no resistance means that the piston or cylinder wall is worn excessively, or that the cylinder head is loose or looking.

An engine that varies in speed even though the throttle valve or the needle valve is not being moved, probably has an air leak in the crankcase. Other locations of an air leak can be the connections in the fuel line filter, or a pin hole in the fuel line.

CAUTION: Do not remove piston ring from piston unless it is to be replaced with a new part. Once removed, the ring shape will become distorted and should not be reinstalled.

K&B 500 or K&B 100+

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